Fergal Keane talks to Noreen Oliver about why her own experience of overcoming an addiction to alcohol led her to set up two treatment centres. She is now one of this country's leading advocates of abstinence as a goal for all addicts. There are over a quarter of a million people in Britain currently addicted to heroin and crack cocaine. The recovery rate is estimated to be three percent. Noreen Oliver believes that the over reliance on "substitute drugs" like methadone is preventing many addicts getting off drugs altogether.